lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 24 Apr 2013 11:47:35 +0400
From:	Cyrill Gorcunov <>
To:	Ingo Molnar <>
Cc:	Linus Torvalds <>,
	Peter Zijlstra <>,
	"H. Peter Anvin" <>,
	Thomas Gleixner <>,
	David Miller <>,
	Theodore Ts'o <>,
	Linux Kernel Mailing List <>,
	the arch/x86 maintainers <>,
	Network Development <>,
	"" <>,
	Oleg Nesterov <>,
	Frederic Weisbecker <>,
	Lin Ming <>
Subject: Re: Unsigned widening casts of binary "not" operations..

On Wed, Apr 24, 2013 at 09:26:30AM +0200, Ingo Molnar wrote:
> * Linus Torvalds <> wrote:
> > And there's quite a lot of them. Even in my (fairly small) config I use on
> > my desktop. And the first warnings I see are in x86 code:
> > 
> >     arch/x86/kernel/traps.c:405:16: warning: implicit unsigned widening
> > cast of a '~' expression
> >     arch/x86/kernel/cpu/perf_event_p4.c:912:15: warning: implicit unsigned
> > widening cast of a '~' expression
> Hm, the perf_event_p4.c code is indeed confused.
> I think the bug is real but probably benign in effect: we allow narrower 
> values into the MSR register than probably intended. Only a couple of low 
> bits are reserved AFAICS.
> Here's an (untested!) patch that tries to untangle it all: it just moves 
> to clean 64-bit types everywhere - these MSRs are 64-bit wide regardless 
> of whether we run on 32-bit or not.
> Would be nice if someone with a working P4 could test it - Cyrill? [It 
> should also be double checked whether the high words are really not 
> reserved and can be written to ...]

Hi Ingo! Ufortunately I don't have access to real p4 hardware,
thus I'm CC'ing Ming who has been helping a lot in testing
this code pieces.

Still the patch itself is perfectly fine to me

Reviewed-by: Cyrill Gorcunov <>
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to
More majordomo info at

Powered by blists - more mailing lists